Guide extension catheter

ABSTRACT

Guide extension catheters and related methods are disclosed. A guide extension catheter can comprise an elongate tube member, a push member, and a concave track. The elongate tube member can define a lumen and three distinct portions of different diameter. A distal portion can define a first diameter, a proximal portion can define a second diameter which is larger than the first diameter but smaller than a lumen of a guide catheter with which the guide extension catheter is used, and a tapered portion, positioned between the distal portion and the proximal portion, can have a variable diameter. The push member can be eccentrically coupled relative to the tube member and extends proximally therefrom for slidably positioning the tube member within and partially beyond a distal end of the guide catheter. The concave track forms a transition between the tube member and the push member, and defines a partially cylindrical opening leading into the tube member.

CLAIM OF PRIORITY

This non-provisional patent document claims the benefit of priorityunder 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No.62/630,321, entitled “GUIDE EXTENSION CATHETER” and filed on Feb. 14,2018, which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

This patent document relates to medical devices. More particularly, butnot by way of limitation, this patent document relates to guideextension catheters for use with guide catheters.

BACKGROUND

A guide catheter can be employed to gain access to a blood vessel anddeliver interventional devices, such as guidewires, balloon catheters,stents or stent catheters, beyond the guide catheter's distal end. Pooralignment between the guide catheter and the ostia of the blood vesselcan make it difficult to deliver interventional devices to a targetlocation within or distal to the vessel. To improve coaxial alignmentbetween the guide catheter and the blood vessel, a narrower guideextension catheter may be used. A growing desire to use larger guidecatheters in tandem with smaller guide extension catheters increases thelikelihood of stent-device interaction at the transition of the guideextension catheter.

OVERVIEW

The present inventors recognize that there is a need to provide guideextension catheters that are compatible with larger guide catheters forperforming interventional procedures in challenging anatomy, e.g.,narrow blood vessels, often harboring robust occlusions. A guideextension catheter that includes tapered guide extension tubing can beused in conjunction with a guide catheter to access discrete regions ofcoronary or peripheral vasculature and to facilitate accurate placementof interventional devices without causing collar transitioninteractions. The guide extension catheter can also include a slidablemanipulation member and/or in some examples, a concave track leadinginto the guide extension tubing.

Guide extension catheters and related methods are disclosed in thispatent document. A guide extension catheter can comprise an elongatetube member (also referred to as guide extension tubing) and a pushmember. At least a portion of the guide extension tubing can be tapered,enabling interventional devices to be funneled to distal portions of theextension tubing, which can be sized smaller to fit into distal vessels.

These and other embodiments and features of the present guide extensioncatheters and related methods will be set forth, at least in part, inthe following Detailed Description. This Overview is intended to providenon-limiting embodiments of the present subject matter—it is notintended to provide an exclusive or exhaustive explanation of thedisclosed embodiments. The Detailed Description below is included toprovide further information about the present guide extension cathetersand methods.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like numerals can be used to describe similar featuresand components throughout the several views. The drawings illustrategenerally, by way of example, but not by way of limitation, variousembodiments discussed in this patent document.

FIG. 1 illustrates a plan view of a guide catheter advanced through anaorta to an ostium of a coronary vessel.

FIG. 2 illustrates a plan view of a guide extension catheter, asconstructed in accordance with at least one embodiment, used inconjunction with a guide catheter for the delivery of an interventionaldevice into an occluded vessel for treatment.

FIG. 3 illustrates a side view of a guide extension catheter, asconstructed in accordance with at least one embodiment, partially withina sectioned guide catheter.

FIGS. 4-6 illustrate cross-sectional views along the length of a guideextension catheter, as constructed in accordance with at least oneembodiment, within a guide catheter.

FIG. 7 illustrates a side view of a guide extension catheter, asconstructed in accordance with at least one embodiment, and aninterventional device partially within a sectioned guide catheter.

The drawings are not necessarily to scale. Certain features andcomponents may be shown exaggerated in scale or in schematic form, andsome details may not be shown in the interest of clarity andconciseness.

DETAILED DESCRIPTION

This patent document discloses guide extension catheters to be placedwithin guide catheters for providing support and guidance in a vesselwhen percutaneously advancing interventional devices, such asguidewires, balloon catheters, stents or stent catheters. A guideextension catheter is configured to be passed through a main lumen of aguide catheter so that its distal end portion can be extended past adistal end of the guide catheter and into the desired vessel while itsintermediate portions remain within the guide catheter. The guideextension catheter improves the ability of the guide catheter to remainseated in the desired vessel's ostium or branch during an interventionalprocedure.

It is believed that the present guide extension catheters will findgreat utility by interventional cardiologists performing percutaneoustransluminal coronary interventions. Although the remainder of thispatent document generally discusses and illustrates such uses, it shouldbe understood that the guide extension catheters can also be used fortreating other non-coronary diseased vessels or other hollow structures(e.g., biliary tract, ureter, etc.) throughout a patient's body whereinterventional devices are or can be employed.

Minimally-invasive cardiac interventions are utilized throughout theworld and include the use of a guidewire 112 and a guide catheter 102,as illustrated in FIG. 1. The guidewire 112 is an elongate,small-diameter member designed to navigate vessels to reach a diseasedsite or vessel segment of interest. Guidewires come in two basicconfigurations: solid steel or nitinol core wires and solid core wirewrapped in a smaller wire coil or braid. The guide catheter 102 is anelongate tube member defining a main lumen 104 along its length. Theguide catheter 102 can be formed of polyurethane, for example, and canbe shaped to facilitate its advancement to a coronary ostium 106 (orother region of interest within a patient's body). In the embodiment ofFIG. 1, a 6F, 7F or 8F guide catheter 102, where F is an abbreviationfor the French catheter scale (a unit to measure catheter diameter (1F=⅓mm)), can be inserted at a femoral or radial artery and advanced throughan aorta 108 to a position adjacent to the ostium 106 of a coronaryartery 110.

In a typical procedure, the guidewire 112 and guide catheter 102 areadvanced through the arch 114 of the aorta 108 to the ostium 106. Theguidewire 112 or, alternatively, a more flexible treatment guidewirereplacing guidewire 112 is then advanced beyond the ostium 106 and intothe coronary artery 110. The diameter and rigidity of the guidecatheter's distal end 116 oftentimes does not permit the guidewire or alater-inserted interventional device to be advanced beyond the ostium106 and into the coronary artery 110.

Maintaining the position of the guide catheter's distal end 116 at theostium 106 can facilitate the guidewire 112 or other interventionaldevice successfully reaching the diseased site (e.g., a stenotic lesion118) through its further distal advancement. With the guide catheter 102in position, force can be applied to the guidewire's proximal end topush the guidewire 112 to and beyond the lesion 118, and a treatingcatheter (optionally including a balloon or stent) can be passed overthe guidewire 112 to treat the site. The application of force to theguidewire 112 or the treating catheter can sometimes cause the guidecatheter 102 to dislodge from the ostium 106 of the coronary artery 110,and, in such instances, the guidewire or treating catheter must befurther distally advanced independently of the guide catheter'salignment and support to reach the lesion 118. This can occur in thecase of a tough stenotic lesion 118 or tortuous anatomy, where it isdifficult to pass the guidewire 112 or the treating catheter to andbeyond the lesion. A heart's intrinsic beat can also cause the guidecatheter's distal end 116 to lose its positioning or otherwise beshifted so that it no longer is positioned to align and support theguidewire 112 or the treating catheter into the portion of the coronaryartery 110 including the lesion 118.

As illustrated in FIG. 2, the present guide extension catheter 200 canimprove access to a coronary artery 210 and a stenotic lesion 218. Theguide extension catheter 200 can include a relatively flexible elongatetube member 220 and a push member 222 having a collective length that isgreater than a length of a guide catheter 202 (e.g., 130 cm-175 cm). Anouter diameter of the tube member 220 can be sized to permit insertionof its distal end portion 224 into a coronary artery or its branchescontaining the lesion 218, thereby providing alignment and support foran interventional device (e.g., a treating catheter) beyond the distalend 216 of the guide catheter 202 to the lesion and beyond. Theextension of the tube member 220 into the smaller-sized artery or branchalso serves to maintain the position of the guide catheter 202 at anartery's ostium 206 during a procedure.

The operating physician can advance the narrow, distal end portion 224of the tube member 220 over a guidewire 212 and through and beyond theguide catheter's distal end 216 into the coronary artery 210. A wider,proximal end portion 226 of the tube member 220 can remain within theguide catheter 202. The physician can then deliver the treating catheterover the guidewire 212, through a main lumen 204 of the guide catheter202, and through a lumen 228 of the tube member 220 until the workingportion of the treating catheter is located beyond the distal endportion 224 of the tube member. The operating physician can then treatthe lesion 218 using standard techniques.

In general, the lumen 228, and hence the tube member 220, can be sizedand shaped to pass one or more interventional devices such as theguidewire and the treating catheter therethrough. The cross-sectionalshape of the lumen 228 can vary along the length of the tube member 220.For instance, the proximal portion 226 of the tube member can have alarger diameter than the distal portion 224. The proximal and distalportions can be separated by a tapered portion 225. The length of eachcross-sectionally-sized portion of the tube member 220 can also vary,and in some examples, the distal portion 224 of the tube member is thelongest. The largest outer diameter of the tube member 220 can assumemaximum cross-sectional dimensions that allow the tube member 220 tocoaxially slide into and through the guide catheter 202. In otherembodiments, the outer cross-sectional dimensions of the tube member 220can be less than the allowable maximum. For example, in an 8F guidecatheter, the tube member 220 can have a 7F, 6F, 5F, 4F or lesserdiameter, depending on the location along the tube member. In someembodiments, the largest diameter of the lumen 228 of the tube member220 is not more than about one French size (e.g., 0.013-0.015 inches)smaller than a diameter of the lumen 204 of the guide catheter 202. Insome examples, the difference in diameter between the proximal portion226 and distal portion 224 of the tube member may be about 1F, 2F, 3F,or 4F. The length of the tube member 220 can be substantially less thanthe length of the guide catheter 202; however, the tube member 220 canbe designed with any length according to a desired application, such asabout 6 cm-45 cm.

The push member 222 can be operably attached to the proximal end portion226 of the tube member 220 and can extend proximally from thisattachment to a handle (also referred to as a manipulation) member 230accessible to an operating physician outside of a patient's body. Thehandle member 230 and the push member 222 can allow the physician toposition the tube member 220 between a first position, entirely withinthe guide catheter 202, and the illustrated second position, in whichthe tube member's distal end 224 extends beyond that of the guidecatheter 202 and into the coronary artery 210.

FIG. 3 illustrates a side view of a guide extension catheter 300partially positioned within a guide catheter 302. This side viewillustrates in greater detail the components of the extension catheter300, including a relatively flexible elongate tube member 320 and a pushmember 322, as well as the distinct portions of the tube member definedby different diameters. For instance, the tube member 320 in the exampleshown defines a narrow distal portion 324, a tapered middle portion 325,and a wider proximal portion 326. The proximal portion 326 is connectedto a concave track 328 which defines variable degrees of enclosure alongits length. As further shown, the push member 322 can be coupled with amanipulation member 330 configured to facilitate pushing of theextension catheter 300 into the guide catheter 302.

The diameter variation of the tube member 320 uniquely equips the guideextension catheter 300 for complex percutaneous coronary interventionalcases performed in distal, narrow blood vessels. Such cases may requirea relatively large guide catheter, e.g., 7F or 8F, in combination with asmaller guide extension profile, e.g., 5F or 6F. Embodiments of the tubemember 320 can include a proximal end portion 326 having a diameter ofabout 7F or 8F, which narrows along tapered portion 325 to a diameter ofabout 6F in the distal end portion 324. The length of each portion oftube member 320 can vary. In one embodiment, the proximal end portion326 may be about 5 cm long, the tapered portion 325 may be about 5 mmlong, and the distal end portion 324 may be about 20 cm long. In otherexamples, the length of the proximal portion 326 may range from about 1cm to about 10 cm, the length of the distal portion 324 may range fromabout 10 cm to about 30 cm, and the length of the tapered portion 325may range from about 2 mm to about 20 mm. Generally, the narrow distalend portion 324 constitutes the majority of the length of the tubemember 320, and in some examples, may be at least twice as long as thetapered portion 325 and the proximal portion 326 combined. The length ofthe tapered portion 325 may be modified without adjusting the differencein diameter between the proximal and distal end portions of the tubemember 320, such that the pitch of the tapered surfaces is steeper forshorter tapered portions and more gradual for longer tapered portions.

The tube member 320 can be formed from an inner polymer layer, an outerpolymer layer, and a reinforcement member (e.g., braid or coil) disposedbetween the polymer layers. The inner polymer layer can be composed of,or coated with, silicone, polytetrafluoroethylene (PTFE) or anotherlubricious material to provide a slippery surface for receivedinterventional devices. The outer polymer layer can include one or moreflexible materials, such as polyurethane, polyethylene or polyolefin ofsequentially diminishing durometers along the tube member's length, andit can be coated with a friction-reducing material (e.g., a hydrophilicmaterial) to facilitate insertion and trackability through vasculatureand a guide catheter. The reinforcing braid or coil can be formed ofstainless steel, nitinol or a platinum alloy, for example, and canextend between the polymer layers along at least a portion of the tubemember's length.

Methods of manufacturing the guide extension catheters described hereinmay involve stretching an inner PTFE lining of the tapered, elongatetube member 320. Because the PTFE lining may require excess stretchingrelative to manufacturing of comparable, but non-tapered tube members,the outer surface of the lining can be etched to maintain the desiredpolymer chemistry of the PTFE, thereby ensuring adhesion between thefluoropolymers of the lining and an outer polymer layer (e.g., Pebax®)wrapping.

The reinforcement member disposed between the polymer layers of theelongate tube member 320 can be configured and assembled in multipleways. For example, if the reinforcement member disposed between thepolymer layers of the elongate member 320 is a coil, three general typesof coils may be used, each coil coupled with other components of thetube member 320 in a distinct manner. If the size of the coil matchesthe smaller distal portion 324 of the tube member 320, the coil can befirst loaded over the distal portion 324 and then turned up against thepitch of the tapered portion 325. By turning the coil against the pitchof the tapered portion 325, the coil diameter will be enlarged such thatthe coil can be loaded over the taper and the larger diameter of theproximal portion 326. If the size of the coil is larger, such that itapproximately matches the larger diameter of the proximal portion 326,the coil can be first loaded onto the proximal portion 326 and thenturned down to match the smaller diameter of the tapered 325 portion anddistal portion 324. If the size of the coil is between the smallerdiameter of the distal portion 324 and the larger diameter of theproximal portion 326, coupling the coil to the tube member 320 mayinvolve a hybrid approach of winding the coil up and down the pitch ofthe tapered portion 325.

In certain embodiments, the push member 322 can include a plurality ofsegments or portions having different stiffness and flexibility profilesto provide the guide extension catheter 300 with a desired combinationof pushing force and vessel placement capabilities. In some examples,the push member 322 can include three segments 334, 336, 338 havingdifferent stiffness and flexibility profiles: relative high stiffnessand low flexibility at a proximal end portion of the push member,relative medium stiffness and flexibility at a proximal end portion ofthe push member, and relative low stiffness and high flexibility at adistal portion of the push member. In some embodiments, the length ofthe first segment 334 makes up between 50% to 90% of the entire lengthof the guide extension catheter 300, the length of the third segment 338makes up between 2% to 10% of the catheter's length, and the remaininglength can be attributed to the second segment 336. More or lesssegments of differing stiffness and flexibility profiles can also beused and accomplished through variation of one or more of materials,geometrical shapes or geometrical sizes of the push member 322. The pushmember 322 can be an elongated solid wire of constant or varyingdimensions and can made of a polymeric or metallic material, such ashigh tensile stainless steel (e.g., 304V, 304L or 316LV), mild steel,nickel-titanium alloys, nickel-chromium-molybdenum alloys, nickel-copperalloys, nickel-tungsten alloys or tungsten alloys. The push member 322can be coated with a hydrophilic, silicone or other friction-reducingmaterial. A handle member (FIG. 2) at the push member's proximal end canbe formed of a polycarbonate material, for example.

The manipulation member 330 facilitates pushing of the extensioncatheter 300 through the guide catheter 302. As shown, the manipulationmember 330 can comprise a tab, which may be cylindrical, that isslidable along the push member 322. In operation, the manipulationmember 330 can be initially positioned proximal to the elongate tubemember 320, and then slid proximally along the push member 322 as theextension catheter 300 is urged distally, toward the treatment site. Insome examples, the manipulation member 330 is engageable with the pushmember 322 via a compressive force applied by a user, e.g., a manualforce applied by a user's thumb.

The concave track 328 can be eccentrically coupled to a distal endportion 340 of the push member 322 at its periphery or circumference andcan provide a smooth transition between the tube member 320 and the pushmember 322. The concave track 328 can be bonded between or integratedwith the proximal end portion 326 of the tube member 320 and/or thedistal end portion 340 of the push member 322. Metallic or polymericstructures forming the concave track 328 can become less stiff and moreflexible in a proximal-to-distal direction to provide a gradualflexibility transition between the more rigid push member 322 and themore flexible tube member 320.

The degree of enclosure defined by the concave track 328 can vary alongthe length of the track. In an embodiment, a first segment 328 a of theconcave track 328 can define an approximately 200° enclosure, a secondsegment 328 b of the concave track can define an approximately 170°enclosure, and a third segment 328 c, closer to the tube member 320, candefine an approximately 200° enclosure, which transitions to 360° justbefore reaching the most proximal end of the tube member's proximalportion 326. Accordingly, the concave track 328 may transition,proximally to distally, from more enclosed to less enclosed, and back tomore enclosed before reaching the proximal end portion 326 of the tubemember 320. The specific degree of enclosure defined by each portion ofthe concave track 328 may vary. For example, the degree of enclosuredefined by each portion may be increased or decreased by up to 5°, 10°,15°, 20°, 25°, 30°, 40°, 50°, 60°, or more. The intermediary valley ofthe concave track, i.e., the second segment 328 b, along with theembedded push member 322, may be urged to one side of the guidecatheter's inner wall surface such that the track 328 and push member322 may be concentrically aligned within guide catheter 302, therebyproviding a clear path through the guide catheter and into the tubemember 320 for a guidewire and a treating catheter. This clear path caneliminate twisting and prevent a guidewire, e.g., guidewire 212, frombecoming entangled with, e.g., wrapped around, the push member 322during use of the guide extension catheter 300. Alleviation of twistingmay be especially apparent in operations requiring multiple,simultaneously inserted guidewires.

In some embodiments, the concave track 328 can define a partiallycylindrical opening, e.g., resembling a half-pipe, and having a lengthof about 1 cm to about 18 cm, 20 cm, 22 cm, 24 cm, 26 cm, or more. Inone example, the concave track 328 may be about 17 cm long. In variousembodiments, the length of each discernible portion 328 a, 328 b, 328 cof the concave track 328 may range from about 1 cm, 2 cm, 4 cm, 6 cm, 8cm, 10 cm, or 12 cm. The length of each portion 328 a, 328 b, 328 c maybe the same or different. The concave track 328 is accessible from alongitudinal side defined transverse to a longitudinal axis of the tubemember 320 and provides a larger area to receive an interventionaldevice into the tube member than an area associated with an openingoriented perpendicular to the longitudinal axis of the tube member 320.Optionally, the concave track 328 can be sized larger than the proximalend portion 326 of the tube member 320 to more effectively align andfunnel a treating catheter across the coupling transition and into thetube member 320. This larger size of the concave track 328 can beaccomplished by incorporating a nickel-titanium alloy, for example,which can expand post-implant to a size of the guide catheter's innerwall surface. Markers on the push member 322 and/or the tube member 320can allow an operating physician to identify positioning of the guideextension catheter's components relative to patient anatomy, the guidecatheter 302, and any international devices used during a procedure. Forexample, one or more depth markers can be printed on an outer surface ofthe push member 322 and can be positioned at predetermined lengthsrelative to a distal end of the tube member 320.

One or more radiopaque marker bands can be positioned on the tube member320. The marker bands can be composed of tungsten, platinum or an alloythereof and can have a metallic band structure. Alternatively, for spaceconservation reasons, the marker bands can be formed by impregnatingportions of the tube member 320 with a radiopaque filler material, suchas such as barium sulfate, bismuth trioxide, bismuth carbonate, powderedtungsten, powdered tantalum or the like. A first marker band can bepositioned slightly distal to a fully-round entrance of the tube member320 and a second marker band can be positioned near the tube member'sdistal end, for example.

FIG. 4 illustrates a cross-sectional view of a proximal end portion 434of a push member 422, such as along line 4-4 of FIG. 3, within a guidecatheter 402. The cross-section can be defined by an arcuate firstsurface 444 configured to engage an inner wall surface 446 of the guidecatheter 402 along an arc length (l₁) (e.g., 0.030 in) defined by aguide catheter central angle (α) of at least 20 degrees, at least 30degrees, at least 40 degrees, at least 50 degrees or at least 60degrees, with greater arc lengths (l₁) associated with greater centralangles (α). The arcuate or curved shape of the first surface 444 followsthe inner wall surface 446 of the guide catheter 402 providing smoothrelative movements between the guide extension catheter and the guidecatheter. The arcuate shape of the first surface 444 can also help tomaximize axial or column strength of the push member 422 for forcetransfer from an operating physician to the rest of the guide extensioncatheter without reducing the effective delivery area 448 within theguide catheter 402 through which an interventional device can beadvanced. In an embodiment, the first surface 444 can have the same orsubstantially the same radius of curvature (r₁) as the guide catheter'sinner wall surface 446, such as a radius of curvature of about 0.035 in.

A second surface 450 of the proximal end portion's cross-section, whichis positioned opposite the first surface 444, can be flat orsubstantially flat and have a length (l₂) (e.g., 0.026 in) that is lessthan the arc length (l₁) of the first surface. The second surface 450can be spaced furthest from the first surface at its center point (c₂).In an embodiment, the center point (c₂) of the second surface 450 is atleast 0.010 in (e.g., 0.014 in) from a center portion (c₁) of the firstsurface 444. In an embodiment, a distance between center points (c₁, c₂)of the first and second surfaces 444, 450 can be between 40-60% of thearc length (l₁) of the first surface.

The cross-section at the proximal end portion of the push member 422 canbe further defined by third and four arcuate surfaces 452, 454 thatconnect the first and second surfaces 444, 450. The third and foursurfaces 452, 454 can have a radius of curvature (r_(3,4)) less than theradius of curvature (r₁) of the first surface 444. In an embodiment, theradius of curvature (r₁) of the first surface (e.g., 0.035 in) is atleast three times greater than the radius of curvature (r_(3,4)) of thethird and fourth surfaces (e.g., 0.010 in).

It has been found that this cross-sectional configuration of theproximal end portion 434 of the push member 422 can be desirable for anumber of reasons. The configuration, which resembles a bread loaf inits cross-sectional shape, can increase the push force capability andthe torque control of the push member 422 as compared to a flatrectangular ribbon. Accordingly, greater axial and rotational forceapplied by the operating physician to the push member's proximal endportion 434 can be transmitted to the tube member. In this manner, thetube member can more reliably be urged through obstructions or into atortuous portion of the patient's vasculature.

FIG. 5 illustrates a cross-sectional view of an intermediate portion 536of a push member 522, such as along line 5-5 of FIG. 3, within a guidecatheter 502. As shown, the intermediate portion 536 can be circular oroval in cross-section and defined by a circumferential surface 537,which can reduce the tendency for a guidewire to become engaged with thepush member 522 during use. In an embodiment, the circumferentialsurface 537 has a diameter of about 0.013 in.

Alternatively, the intermediate portion 536 can be rectangular incross-section and defined by first, second, third and fourth flatsurfaces, or can be bread loaf in cross-section and defined by threearcuate surfaces and one flat surface like the proximal end portion. Inthese alternative embodiments, a distance change between center pointsof the first and second surfaces at the push member's proximal endportion (FIG. 4) to center points of the first and second surfaces atthe push member's intermediate portion is less than a distance changebetween center points of the third and fourth surfaces at the pushmember's proximal end portion to center points of the third and fourthsurfaces at the push member's intermediate portion.

Yet another alternative, the intermediate portion 536 can have across-section defined by arcuate first and second surfaces. An arcuatefirst surface can have the same or substantially the same radius ofcurvature as the guide catheter's inner wall surface. An arcuate secondsurface can extend from a first end of the first surface to a second endof the first surface. Regardless of shape, the cross-section of theintermediate portion 536 of the push member can define an area less thanan area of the cross-section of the proximal end portion (FIG. 4) of thepush member 522.

FIG. 6 illustrates a cross-sectional view of a distal end portion 638 ofa push member 622, such as along line 6-6 of FIG. 3, within a guidecatheter 602. The distal end portion 638 can be rectangular incross-section and defined by first, second, third and fourth flatsurfaces 656, 658, 660, 662. The cross-section of the distal end portion638 can define an area less than an area of the cross-section of theproximal end (FIG. 4) and intermediate (FIG. 5) portions of the pushmember 622. In an embodiment, the first and second surfaces 656, 658have a length of 0.020 in., and the third and fourth surfaces 660, 662have a length of 0.010 in. The cross-section of the stiffer proximal endportion can gradually transition along the length of the push member 622to the more flexible cross-section of the distal end portion 638, whichcan couple to a tube member 620. The flattened rectangular cross-sectionof the distal end portion 638 can provide sufficient attachment surfacearea to attach the push member 622 to the tube member 620.Alternatively, the distal end portion 638 can be bread loaf incross-section and defined by three arcuate surfaces and one flat orsubstantially flat surface like the proximal end portion.

FIGS. 4-6 illustrate that the push member 422, 522, 622 of a guideextension catheter can be designed to be sufficiently small taking uprelatively little space within the lumen of a guide catheter, whilestill being sufficiently sized and configured for exceptionalpushability and kink resistance when advancing the extension catheterduring an interventional procedure. Accordingly, use of the presentguide extension catheters allows for an interventional device to beadvanced through and beyond the guide catheter to reach a desired distaltarget location for intervention.

FIG. 7 illustrates a side view of a guide extension catheter 700positioned within a guide catheter 702 and used in conjunction with aguidewire 712 and a treating catheter 764. With the guidewire 712 andthe guide catheter 702 positioned as desired, a tube member 720 of theguide extension catheter 700 can be backloaded from its narrow distalend portion 724 onto a proximal end of the guidewire 712 and advancedthrough a hemostasis valve coupled to the guide catheter 702. As shown,the tube member 720 of the guide extension catheter 700 can be advancedbeyond a distal end 716 of the guide catheter 702 under fluoroscopy.When so arranged, portions of the tube member 720 can engage an ostiumand extend within a portion of a coronary artery to help maintain theposition of the guide catheter 702 as the treating catheter 764 isadvanced. The variable degree of enclosure provided by the concave track728 at portions 728 a, 728 b, and 728 c may prevent twisting of theguidewire 712.

EXAMPLES

The above Detailed Description is intended to be illustrative and notrestrictive. The above-described embodiments (or one or more features orcomponents thereof) can be used in varying combinations with each otherunless clearly stated to the contrary. Other embodiments can be used,such as by one of ordinary skill in the art upon reviewing the aboveDetailed Description. Also, various features or components have beengrouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter can lie in lessthan all features of a particular disclosed embodiment. Thus, thefollowing claim examples are hereby incorporated into the DetailedDescription, with each example standing on its own as a separateembodiment.

In Example 1, a guide extension catheter for use with a guide cathetercan comprise an elongate tube member defining a lumen and threeportions. Each portion can have a distinct diameter. The tube member cancomprise a distal portion having a first diameter, a proximal portiondefined by a second diameter which is larger than the first diameter butsmaller than a lumen of the guide catheter, and a tapered portion,positioned between the distal portion and the proximal portion, definedby a variable diameter. The guide extension catheter can also include apush member eccentrically coupled relative to the tube member andextending proximally therefrom for slidably positioning the tube memberwithin and partially beyond a distal end of the guide catheter. Inaddition, the guide extension catheter can include a concave trackcoupled to the tube member and the push member. The concave track candefine a partially cylindrical opening leading into the tube member

In Example 2, the guide extension catheter of Example 1 can optionallybe configured such that the first diameter is about 6F or less.

In Example 3, the guide extension catheter of Example 1 or 2 canoptionally be configured such that the second diameter is about 7F orgreater.

In Example 4, the guide extension catheter of any one or any combinationof Examples 1-3 can optionally be configured such that the distalportion is at least twice as long as the proximal portion and thetapered portion combined.

In Example 5, the guide extension catheter of any one or any combinationof Examples 1-4 can optionally be configured such that the distalportion is about 20 cm long.

In Example 6, the guide extension catheter of any one or any combinationof Examples 1-5 can optionally be configured such that the proximalportion is about 5 cm long.

In Example 7, the guide extension catheter of any one or any combinationof Examples 1-6 can optionally be configured such that the taperedportion is about 5 mm long.

In Example 8, the guide extension catheter of any one or any combinationof Examples 1-7 can optionally be configured such that the concave trackdefines an intermediary track portion that is less enclosed than adistal track portion and a proximal track portion.

In Example 9, the guide extension catheter of Example 8 can optionallybe configured such that an enclosure of the intermediary portion isabout 170°, an enclosure of the distal track portion is about 200°, andan enclosure of the proximal track portion is about 200°.

In Example 10, the guide extension catheter of any one or anycombination of Examples 1-9 can optionally comprise a slidablemanipulation member coupled with the push member. The slidablemanipulation member can comprise a tab that defines a hole through whichthe push member is urged during insertion of the guide extensioncatheter through the guide catheter.

In Example 11, the guide extension catheter of any one or anycombination of Examples 1-10 can optionally be configured such that areinforcement member comprising a coil is coupled with the elongate tubemember.

In Example 12, the guide extension catheter of Example 11 can optionallybe configured such that the coil, in a relaxed state, defines a diameterthat approximately matches the second diameter.

In Example 13, the guide extension catheter of Example 12 can optionallybe configured such that the coil is wound down over the tapered portionduring assembly.

In Example 14, the guide extension catheter of Example 11 can optionallybe configured such that the coil, in a relaxed state, defines a diameterthat approximately matches the first diameter.

In Example 15, the guide extension catheter of Example 14 can optionallybe configured such that the coil is wound up over the tapered portionduring assembly.

In Example 16, the guide extension catheter of Example 11 can optionallybe configured such that the coil, in a relaxed state, defines a diameterthat is between the first diameter and the second diameter.

In Example 17, the guide extension catheter of Example 16 can optionallybe configured such that the coil is wound up over the proximal portionand wound down over the distal portion during assembly.

In Example 18, the guide extension catheter of any one or anycombination of Examples 1-17 can optionally be configured such that theelongate tube member comprises an inner polymer layer.

In Example 19, the guide extension catheter of Example 18 can optionallybe configured such that the inner polymer layer is stretched duringassembly of the elongate tube member.

In Example 20, the guide extension catheter of Example 19 can optionallybe configured such that after stretching, an outer surface of the innerpolymer layer is etched.

CLOSING NOTES

The above Detailed Description includes references to the accompanyingdrawings, which form a part of the Detailed Description. The DetailedDescription should be read with reference to the drawings. The drawingsshow, by way of illustration, specific embodiments in which the presentguide extension catheters and related methods can be practiced. Theseembodiments are also referred to herein as “examples.”

Certain terms are used throughout this patent document to refer toparticular features or components. As one skilled in the art willappreciate, different people may refer to the same feature or componentby different names. This patent document does not intend to distinguishbetween components or features that differ in name but not in function.For the following defined terms, certain definitions shall be appliedunless a different definition is given elsewhere in this patentdocument. The terms “a,” “an,” and “the” are used to include one or morethan one, independent of any other instances or usages of “at least one”or “one or more.” The term “or” is used to refer to a nonexclusive or,such that “A or B” includes “A but not B,” “B but not A,” and “A and B.”All numeric values are assumed to be modified by the term “about,”whether or not explicitly indicated. The term “about” refers to a rangeof numbers that one of skill in the art considers equivalent to therecited value (i.e., having the same function or result). In manyinstances, the term “about” can include numbers that are rounded to thenearest significant figure. The recitation of numerical ranges byendpoints includes all numbers and sub-ranges within and bounding thatrange (e.g., 1 to 4 includes 1, 1.5, 1.75, 2, 2.3, 2.6, 2.9, etc. and 1to 1.5, 1 to 2, 1 to 3, 2 to 3.5, 2 to 4, 3 to 4, etc.). The terms“patient” and “subject” are intended to include mammals, such as forhuman or veterinary applications. The terms “distal” and “proximal” areused to refer to a position or direction relative to an operatingphysician. “Distal” and “distally” refer to a position that is distantfrom, or in a direction away from, the physician. “Proximal” and“proximally” refer to a position that is near, or in a direction toward,the physician. And the term “interventional device(s)” is used toinclude, but is not limited to, guidewires, balloon catheters, stentsand stent catheters.

The scope of the present guide extension catheters and methods should bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled. In the appendedclaims, the terms “including” and “in which” are used as theplain-English equivalents of the respective terms “comprising” and“wherein.” Also, in the following claims, the terms “including” and“comprising” are open-ended; that is, a device or method that includesfeatures or components in addition to those listed after such a term ina claim are still deemed to fall within the scope of that claim.Moreover, in the following claims, the terms “first,” “second” and“third,” etc. are used merely as labels, and are not intended to imposenumerical requirements on their objects.

The Abstract is provided to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims.

1-20. (canceled)
 21. A catheter comprising: an elongate tube memberextending from a proximal end to a distal end and defining a lumen; apush member mechanically coupled to the proximal end of the elongatetube member; and a manipulation member slidable along the push memberand disposed around an outer perimeter of the push member, wherein themanipulation member is controllably engageable with the push member, andwherein, when the manipulation member is engaged with the push member,the manipulation member is configured to transmit an axial force to theelongate tube member, and when the manipulation member is not engagedwith the push member, the manipulation member is movable in at least onedirection along a length of the push member while transmittingsubstantially no axial force to the push member.
 22. The catheter ofclaim 21, wherein the push member is eccentrically coupled to theproximal end of the elongate tube member.
 23. The catheter of claim 21,wherein the elongate tube member includes a distal portion having afirst diameter, a proximal portion having a second diameter that islarger than the first diameter, and a tapered portion positioned betweenthe distal portion and the proximal portion.
 24. The catheter of claim21, wherein the push member comprises a handle member at or near aproximal end of the push member, and wherein the handle member isconfigured to prevent the manipulation member from being slid off theproximal end of the push member.
 25. The catheter of claim 21, whereinthe manipulation member surrounds the outer perimeter of the push memberso that the manipulation member is not radially removable from the pushmember.
 26. The catheter of claim 21, wherein the manipulation membercomprises at least one engagement feature on an inner surface of themanipulation member, and wherein the at least one engagement feature isconfigured to increase engagement of the inner surface of themanipulation member with the push member.
 27. The catheter of claim 21,wherein the manipulation member comprises a tab configured to beengageable with the push member when a compressive force is applied tothe tab.
 28. The catheter of claim 21, wherein the manipulation memberis configured to default not to being engaged with the push member, andto engage the push member in response to a radially inward force beingapplied to the manipulation member.
 29. A catheter system comprising: aguide catheter extending from a guide catheter proximal end to a guidecatheter distal end and defining a guide catheter lumen; and a guideextension catheter comprising: an elongate tube member extending from aproximal end to a distal end and defining a guide extension catheterlumen; a push member mechanically coupled to the proximal end of theelongate tube member; and a manipulation member slidable along the pushmember and disposed around an outer perimeter of the push member,wherein the manipulation member is controllably engageable with the pushmember, wherein, when the manipulation member is engaged with the pushmember, the manipulation member is configured to transmit an axial forceto the elongate tube member, and when the manipulation member is notengaged with the push member, the manipulation member is movable in atleast one direction along a length of the push member while transmittingsubstantially no axial force to the push member.
 30. The catheter ofclaim 29, wherein the push member is eccentrically coupled to theproximal end of the elongate tube member.
 31. The catheter of claim 29,wherein the elongate tube member includes a distal portion having afirst diameter, a proximal portion having a second diameter that islarger than the first diameter and smaller than a diameter of the guidecatheter lumen, and a tapered portion positioned between the distalportion and the proximal portion.
 32. The catheter system of claim 29,wherein the elongate tube member of the guide extension catheter definesa maximum outer diameter that is less than a diameter of the guidecatheter lumen.
 33. The catheter system of claim 29, wherein the guideextension catheter defines a length that is greater than a length of theguide catheter.
 34. The catheter system of claim 29, wherein the pushmember comprises a handle member at or near the a proximal end of thepush member, and wherein the handle member is configured to prevent themanipulation member from being slid off the proximal end of the pushmember.
 35. The catheter system of claim 29, wherein the manipulationmember surrounds the outer perimeter of the push member so thatmanipulation member is not radially removable from the push member. 36.The catheter system of claim 29, wherein the manipulation membercomprises at least one engagement feature on an inner surface of themanipulation member, and wherein the at least one engagement feature isconfigured to increase engagement of the inner surface of themanipulation member with the push member.
 37. A method comprising:introducing a guide catheter in vasculature of a patient, wherein theguide catheter extends from a guide catheter proximal end to a guidecatheter distal end and defines a guide catheter lumen; introducing aguide extension catheter in the guide catheter lumen at the guidecatheter proximal end, wherein the guide extension catheter comprises anelongate tube member extending from a proximal end to a distal end anddefining a guide extension catheter lumen, a push member mechanicallycoupled to the proximal end of the elongate tube member, and amanipulation member slidably disposed about an outer perimeter of thepush member, wherein the manipulation member is controllably engageablewith the push member, wherein, when the manipulation member is in anengaged state with the push member, the manipulation member transmits anaxial force to the push member to enable the push member to transmit theaxial force to the elongate tube member, and wherein, when themanipulation member is in a disengaged state with the push member, themanipulation member is movable axially in at least one direction along alength of the push member while transmitting substantially no axialforce to the push member; while the manipulation member is in theengaged state with the push member, applying a distal axial force to themanipulation member to advance the guide extension catheter distallywithin the guide catheter lumen; disengaging the manipulation memberfrom the push member; repositioning the manipulation member along thelength of the push member; engaging the manipulation member with thepush member; and while the manipulation member is in the engaged statewith the push member, applying a distal axial force to the manipulationmember to further advance the guide extension catheter distally throughthe guide catheter lumen.
 38. The method of claim 37, wherein the pushmember is eccentrically coupled to the proximal end of the elongate tubemember.
 39. The method of claim 37, wherein introducing the guideextension catheter in the guide catheter lumen includes introducing anelongate tube member including a distal portion having a first diameter,a proximal portion having a second diameter that is larger than thefirst diameter and smaller than a diameter of the guide catheter lumen,and a tapered portion positioned between the distal portion and theproximal portion.
 40. The method of claim 37, further comprisingadvancing a balloon catheter, a stent, or a stent catheter through theguide catheter and the guide extension catheter and into a coronaryartery of the patient.